Nokea
Peptide hormones function by binding to receptor proteins within the ________. Once the hormone binds to a receptor, it activates ______.
- A. cell: a second messenger
- B. cell: particular genes
- C. plasma membrane: a second messenger
- D. plasma membrane: particular genes
Correct Answer: C
Rationale: The correct answer is C because peptide hormones typically bind to receptor proteins on the plasma membrane. This is because peptide hormones are not able to pass through the cell membrane due to their size and polarity. Once the hormone binds to the receptor on the plasma membrane, it activates a second messenger system within the cell, leading to various cellular responses.
Choice A is incorrect because peptide hormones do not bind directly to intracellular components like second messengers inside the cell. Choice B is incorrect because peptide hormones do not directly activate particular genes within the cell. Choice D is incorrect because peptide hormones do not bind directly to genes on the plasma membrane.
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The parathyroid glands maintain adequate levels of blood calcium. This is accomplished through ________.
- A. blocking the action of growth hormone
- B. targeting the bone and activating osteoclasts so that calcium will be released
- C. antagonizing the synthesis of calcitonin
- D. slowing the activity of tissues that require calcium for activity
Correct Answer: B
Rationale: The correct answer is B because the parathyroid glands target the bone and activate osteoclasts to release calcium into the bloodstream. This process helps maintain adequate blood calcium levels. By activating osteoclasts, calcium is released from the bone into the blood, ensuring a balance of calcium levels.
A: Blocking the action of growth hormone is unrelated to the function of parathyroid glands in maintaining blood calcium levels.
C: Antagonizing the synthesis of calcitonin is not the primary mechanism through which parathyroid glands regulate blood calcium levels.
D: Slowing the activity of tissues that require calcium for activity would not help maintain adequate blood calcium levels as it does not address the direct release of calcium from bone by activating osteoclasts.
Catecholamines:
- A. include cortisol, aldosterone, and testosterone.
- B. are secreted by the adrenal cortex.
- C. lower plasma glucose levels.
- D. include epinephrine (adrenalin) and norepinephrine.
Correct Answer: D
Rationale: Rationale for Correct Answer D: Catecholamines include epinephrine and norepinephrine. These hormones are produced by the adrenal medulla in response to stress and play a crucial role in the fight-or-flight response. Epinephrine increases heart rate and blood flow to muscles, while norepinephrine helps maintain blood pressure. These actions help the body respond to stressful situations.
Summary of Other Choices:
A: Incorrect. Cortisol, aldosterone, and testosterone are not catecholamines. They are steroid hormones produced by the adrenal cortex.
B: Incorrect. Adrenal cortex secretes cortisol and aldosterone, not catecholamines.
C: Incorrect. Catecholamines actually increase plasma glucose levels to provide energy during stress.
Which form of intestinal smooth muscle contraction does NOT occur in normal health?
- A. peristalsis
- B. weak antiperistalsis
- C. peristaltic rushes
- D. tonic contractions
Correct Answer: C
Rationale: The correct answer is C: peristaltic rushes. Peristaltic rushes are abnormal and excessive contractions that can result in diarrhea or bowel urgency. In normal health, peristalsis (A) is the coordinated contraction and relaxation of intestinal smooth muscles that moves contents along the digestive tract. Weak antiperistalsis (B) refers to reverse contractions that are weaker than normal peristalsis. Tonic contractions (D) are sustained contractions that help maintain muscle tone and control flow. Therefore, peristaltic rushes are the only option that does not occur in normal health due to their abnormal and disruptive nature.
Annabelle has been referred to an endocrinologist for evaluation of the following symptoms: infertility, hypogonadism, and delayed puberty. Which hormone(s) from the pituitary is/are lacking in Annabelle?
- A. FSH and LH.
- B. ACTH.
- C. TSH.
- D. Growth hormone.
Correct Answer: A
Rationale: Infertility, hypogonadism, and delayed puberty in women are commonly due to a deficiency in the pituitary hormones FSH and LH, which regulate reproductive function.
What is the speed of the wave?
- A. 1.5cm/s
- B. 3.0cm/s
- C. 300 cm/s
- D. 600 cm/s
Correct Answer: D
Rationale: The correct answer is D: 600 cm/s. The speed of a wave is determined by the formula speed = frequency x wavelength. Given that the frequency and wavelength are constant, the only way to increase the speed is to increase the frequency or the wavelength. Since both frequency and wavelength are fixed, the speed can only be increased by increasing both. Choice D, 600 cm/s, is double the speed of choice C, 300 cm/s, which indicates that both frequency and wavelength have been doubled, leading to the correct answer. Choices A and B are too low to be correct, as they are not consistent with the principles of wave speed calculation.